repoze.who.recaptcha implements server side of the recaptcha API. This IAuthenticator plugin examines environment for recaptcha form values and requests verification.

repoze.who.recaptcha works based on form_handler condition:

if form_handler parameter is not given, always perform authentication.

if form_handler parameter is given, perform authentication only when one of the form_handler values (separated by space) matches the absolute URL where the form is processed.

If the validation succeeds, no action is taken. Otherwise error is passed to environ['repoze.who.error'] and HTTPUnauthorzied(401) is triggered.

Public Mercurial repo is avaliable at bitbucket.org

# sample .ini configuration

[plugin:recaptcha]
use = repoze.who.plugins.captcha:make_authentication_plugin
private_key = si3di5ndlam3x44d
#optional
form_handler = /process /login /admin

[authenticators]
plugins =
        recaptcha